ALLO USBridge Signature and Digione Sig

[suzywong]

For a USBSig & DigiOneSig, you need to have the correct case, on the relevant page  on the allo.com site is a drop down for “USBridgeSig+DigiOne Sig”. Then you will find that the “dirty” supply is the USB-C, bottom left, and the “clean” supply is the barrel connector,  top right. 

 

Note that depending on the age of your existing DigiOneSig, you may have to short out a diode on the middle lower board of the DigOneSig (and if it’s really old, a diode on the top board). 

 

You could run the whole caboodle from a single power supply feeding both clean and dirty supplies, and indeed I did exactly that for a few months with a Cuinas Audio ISO-PS, and very fine it was

 

But for maximum benefit what you need is two isolated supplies: for example, your bog standard RPi supply for the dirty side and a separate “low noise” LPS or even batteries for the clean side, or a dedicated dual (isolated) output PS, such as Allo’s Shanti.

 

I run my USBSig+Digi1Sig+Shanti+Moode through Naim DC-1 BNC-BNC interconnect to a Naim DAC+XPS.

 

It is really rather good!

[suzywong]

Ignore, double post

[suzywong]

Right, this sounds like you need to do the diode shorting mod on the middle board of the DigiOneSig+USBridgeSig stack.

 

I did it  the same way (ran the DigiSig with a RPi 3B+ at first, then bought the USBSig & case later on). I could get the whole stack to run only if I took the top off and used both power inputs on the DigiOneSig.

 

I've added the two photos. You may find the top board already has a link in place, but the middle board will almost certainly need attention.

 

You don't have to remove the diode, just solder a bit of TCW across it.

 

 

[suzywong]

The DigiOneSig+USBSig case has two power connectors on the rear panel.

 

1. USB-C type for the dirty side, located bottom left (when looking on the rear face) which connects directly onto the USBSig board. Supply should be rated at +5V, 3A.

 

2. 2.5mm “barrel” type, located top right for the clean side. Internally the barrel connector has a short flying lead endingwith a USB-C type connector that plugs into the clean supply connector on the DigiOne Sig. Supply should be rated at +5V, 1A.

 

If you were running your DigiOneSig on top of an RPi then you will recall that you plugged both clean and dirty supplies into the DigiOneSig and the RPi got its power from the DigiOneSig.

 

Now that you have replaced your RPi with a USBSig, the intention is that you will run the dirty & clean supplies into the rear panel, therefore you will have the internal flying lead connected to the clean side of the DigiOne Sig.

 

However, if then you plug your supplies into the rear panel and it does not work, then that indicates that the middle board (at least) still has the diode. Therefore the mod(s) as described previously will be required.

 

You can confirm this by removing the case top, unplugging the aforementioned barrel to USB-C flying lead, and connecting your supplies directly to the DigiOneSig; the DigiOneSig will then supply power to the USBSig, and indeed I ran the unit with that configuration for a few days, while investigating the problem. The photos were send me by AProbin of this parish; I believe he had obtained them from Allo.

 

 

[suzywong]

Good that you’ve now got it working, and as suspected, it’s the middle board diode causing the problem.

 

I got out the soldering iron and shorted out the diode; it’s a straightforward fix - leave the diode in place and just solder a loop of TCW between the ends - but if you are not confident with wielding an iron, then maybe you could ask Allo to send you a new middle board.

 

For sure, having done mine, I can now power the whole unit via the rear panel. 

 

It’s curious that Allo haven’t been around...they’re normally very quick to respond...and it’s not even August 😆😆.

Maybe they’ve got caught up in this Coronavirus shebackle. If so, then I’m sure we wish them well.

 

[suzywong]

I posted pictures of both boards up this thread.......

 

your top board diode looks like it may already be shorted out, but the picture is not overly clear.

 

on the middle board, i left the diode in place and simply looped a bit of TCW across the terminals.

 

 

[suzywong]

My understanding is that this is no longer an issue.

 

Especially if you get a USBridge SIgnature at the same time 😀